The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
Rotating clutches, that is, devices having both rotating clutch elements and clutch operators, are often utilized within automatic motor vehicle transmissions and similar devices to transmit torque between two rotating components. Upon a suitable command, these clutches engage and disengage by stroking a hydraulically driven piston. When rotating, the oil behind the hydraulic piston in an apply cavity builds pressure due to centrifugal effects. The force thus generated must be countered by an equivalent opposing force in order to prevent unintended piston stroke and clutch engagement. This opposing force is commonly provided by a second volume of oil contained in a balance cavity on the opposite side of the piston. As the rotating clutch spins, centrifugally generated oil pressure and thus force within the apply cavity and the balance cavity cancel each other out.
In prior art transmission configurations, oil utilized within the balance cavity is non-pressurized lubrication oil collected and fed into the balance cavity through centrifugal effects only during rotation. In situations where the rotating clutch is brought to rest, the balance cavity will drain. The apply cavity, however, will remain fluid filled even when the clutch is released. This is done for shift quality considerations. If the clutch with a drained balance cavity is rapidly accelerated, a condition may develop in which the clutch piston is no longer force balanced. These situations are particularly common in hybrid transmissions in which rotating clutches are utilized with electric motors capable of extremely rapid rates of acceleration.